On the Zoomzum blog there's a new post with ten regular expressions PHP developers can use to accomplish some common tasks (like email validation and date formatting checks).

Regular expression for the PHP developers, on of the most popular tool for validating data is the regular expression. In this list we provides some validation – string match, password match validation, email address validation, date format and many more which helps developer to make their application more fast and easy to execute. [...] Have you note that, regular expressions are more slower than the basic string function, its takes a short time to execute than any others.

Included in their list are things like:

Password Match Validation

Validate URL

Validate URL using Preg_match

UK Postcode Validation

SSN,ISBN and Zipcode Validation

A few of these could be done with either one or two string calls or some of the filtering functions that are included in PHP.